Apparatus for preventing circumferential overspeeding of grinding wheel

ABSTRACT

An apparatus for preventing circumferential overspeeding of a grinding wheel in a grinding machine wherein the rotating speed of the grinding wheel spindle is made variable through pulley exchange comprises a grinding wheel head with the grinding wheel spindle rotatably mounted thereto and a motor connected to drive the spindle. For the purpose of averting the hazard of circumferential overspeeding of the grinding wheel a largediameter grinding wheel rejecting pin obstructs the space to be occupied by a large-diameter grinding wheel when a small-diameter high-speed pulley is connected to drive the grinding wheel spindle. This prevents the mounting of a large-diameter grinding wheel. A high-speed pulley rejecting pin is mechanically interlocked with the large-diameter grinding wheel rejecting pin and each moves in the same direction. The high-speed pulley rejecting pin obstructs the space to be occupied by the highspeed pulley when a large-diameter grinding wheel is connected to the spindle thereby preventing the mounting of the high-speed pulley.

United States Patent Koide et al. I

3,673,741 I July 4, 1972 [72] inventors: Tsuyoshi Koide; lkuo Othu, bothof 1,1-

chome, Kariya, Asahimachi, Japan [221 Filed: Sept. 8, 1970 [21]Appl.N0.: 70,040

[30] Foreign Application Priority Data Sept. 16, 1969 Japan ..44/87926[52] US. Cl. ..5l/l34.5 R [51] Int. Cl ..B24b 55/00 [58] Field ofSearch...: ..51/72,134.5,166, 268, 269

[56] References Cited UNITED STATES PATENTS 2,471,561 5/1949 Fielding..51/269 2,487,949 11/1949 Shekels 3,129,534 4/1964 Miyabayashi..51/l34.5

APPARATUS FOR PREVENTING CIRCUMFERENTIAL OVERSPEEDING 0F GRINDING WHEELPrimary Examiner-Donald 0. Kelly Attorney-Connolly & l-lutz [57]ABSTRACT An apparatus for preventing circumferential overspeeding of agrinding wheel in a grinding machine wherein the rotating speed of thegrinding wheel spindle is made variable through pulley exchangecomprises a grinding wheel head with the grinding wheel spindlerotatably mounted thereto and a motor connected to drive the spindle.For the purpose of averting the hazard of circumferential overspeedingof the grinding wheel a large-diameter grinding wheel rejecting pinobstructs the space to be occupied by a large-diameter grinding wheelwhen a small-diameter high-speed pulley is connected to drive thegrinding wheel spindle. This prevents the mounting of a largediametergrinding wheel. A high-speed pulley rejecting pin is mechanicallyinterlocked with the large-diameter grinding wheel rejecting pin andeach moves in the same direction. The high-speed pulley rejecting pinobstructs the space to be occupied by the high-speed pulley when alarge-diameter grinding wheel is connected to the spindle therebypreventing the mounting of the high-speed pulley.

4 Claims, 3 Drawing Figures PATENTEDJUL "4 1912 3, 673 741 sum 10: 2

| l a //l 11a 10c 1% i 12 APPARATUS FOR PREVENTING CIRCUMFERENTIALOVERSPEEDING OF GRINDING WHEEL BACKGROUND OF THE INVENTION The presentinvention relates to a novel device for simply and reliably preventingcircumferential overspeeding of a grinding wheel thereby avoiding thehazard of the grinding wheel being broken with a resultant drop in workefficiency.

In the conventional grinding of a work piece on the periphery of agrinding wheel, the grinding wheel is usually driven by the motor pulleyand the grinding wheel spindle pulley linked by V-belts for transmissionof the motion from the motor. The rotary speed of the grinding wheelspindle is constant when the diameter combination of the two pulleys isgiven. As the grinding wheel is worn away and its diameter reduced, thecircumferential speed of the grinding wheel drops and in consequence thegrinding efficiency falls. For compensation of the drop in thecircumferential speed it is common practice to exchange the pulley. Withreduction of the grinding wheel diameter, either the motor pulley or thegrinding wheel spindle pulley is changed from a low-speed one to ahigh-speed one thereby speeding up the grinding wheel rotation. At thetime when a reduced-diameter grinding wheel is replaced with alarge-diameter wheel, the rotation of the large-diameter grinding wheelwill be excessive due to the high-speed spindle or the motor shaft. Andit will cause an overspeeding of the grinding wheel with the hazard ofbreaking the grinding wheel. If the construction is such that thegrinding wheel and the pulley are separately changeable, an overspeedingof the grinding wheel can easily occur. A safe overspeed preventiondevice free from such hazard has been strongly demanded from industrialcircles.

SUMMARY OF THE INVENTION The object of this invention is to provide amechanism for making it impossible to mount a large-diameter grindingwheel on the grinding wheel spindle while a small-diameter pulley of thegrinding wheel spindle matching a reduced-diameter grinding wheel isleft on, thereby averting the destruction of the grinding wheel due tooverspeeding. Another object of the invention is to make this mechanismsimple and low-priced.

According to this invention, the grinding wheel spindle is rotatablymounted on the grinding wheel head. The motor rotation is transmitted tothe grinding wheel spindle via pulleys and V-belts. The rotating speedof the grinding wheel spindle can be varied by a change in the pulleycombination. ln continued grinding with a large-diameter grinding wheeland a low-speed pulley the circumference of the grinding wheel wearsaway with the result that the diameter diminishes, the circumferentialspeed drops and the work efiiciency falls. A high-speed pulley is thensubstituted for the low-speed pulley to drive the grinding wheel at ahigher rotary speed. Eventually, the grinding wheel with its diameterreduced to a certain limit must be replaced with a large-diameter one.If this replacement is done with the pulley unchanged, thecircumferential speed of the new grinding wheel will become excessiveand may break the grinding wheel. According to this invention, when thehigh-speed pulley is on the grinding wheel spindle, the mounting of alarge-diameter grinding wheel is obstructed by a large-diameter grindingwheel rejecting pin. Also, when the large-diameter grinding wheel is on,the mounting of a high-speed pulley is prevented by a high-speed pulleyrejecting pin.

BRIEF DESCRIPTION OF THE DRAWING Novel features and advantages of thepresent invention in addition to those mentioned above will becomeapparent to one skilled in the art from a reading of the followingdetailed description in conjunction with the accompanying drawingwherein:

FIG. 1 is a side elevational view of an embodiment of the presentinvention;

FIG. 2 is a top plan view of the embodiment shown in FIG. I; and

Lil

FIG. 3 is an enlarged fragmental sectional view of the embodiment ofFIGS. 1 and 2 illustrating the details of the present invention.

DETAILED DESCRIPTION OF THE INVENTION As shown in FIGS. 1 and 2, agrinding wheel 3 is fixed to one end of a grinding wheel spindle 2rotatably mounted on a grinding wheel head 1. A pulley 4-or 33 is fixedto the other end of the spindle 2. A new large-diameter grinding wheel,indicated by reference character a, is mounted on the grinding wheelspindle 2. As the grinding wheel is reduced in diameter to the diameterindicated by reference character b, a pulley exchange is required forrotating the grinding wheel until it reaches the diameter indicated byreference character c. Thereupon, the low-speed pulley 4 matching thelarge-diameter grinding wheel is replaced by the high-speed pulley 33for a reduced-diameter grinding wheel. A grinding wheel guard 5 isattached to the grinding wheel headl to protect the grinding wheel 3. Amotor 8 is attached opposite the grinding wheel 3 on the grinding wheelhead I. The shaft end of the motor is fitted with a motor pulley 18whose axis runs parallel to the grinding wheel spindle 2. The motor 8 isfixed to a motor base 9 slidably mounted along a guide surface la formedon the grinding wheel head 1 perpendicular to the grinding wheel spindle2 so that appropriate tension can be maintained on the V-belts 34stretched between the pulley 4 or 33 mounted on the grinding wheelspindle 2 and the motor pulley 18 mounted on the motor shaft. A handwheel 12 moves the motor 8 via the motor base 9 in relation to thegrinding wheel spindle 2. A feed screw 11 penetrates a feed screwsupport 10 fixed to the grinding wheel head 1 and the feed screw ismanipulated by the hand wheel 12. A step 11a of the feed screw 11 and anend face 12a of the hand wheel 12 squeeze the side faces of the feedscrew support 10 and in this condition the feed screw 11 is axiallyimmovable during rotation. When the hand wheel 12 is turned, the motorbase 9 is shifted along the guide surface 14 and the slack in theV-belts 34 caused through exchange between the large-diameter low-speedpulley 4 and the smalldiameter high-speed pulley 33 is removed. The handwheel 12 is manipulated until the V-belts are adequately tensioned.

A plate 13 is fixed to the side face 1 on the pulley side of thegrinding wheel head 1. A link shaft 14 is supported by the plate 13. Theshaft 14 is rotatably passed through a fixing member 15 fixed on theplate 13 and the shaft is parallel to the grinding wheel spindle 2. Arotatable boss 16 is solidly secured to the pulley side end 14' of thelink shaft 14 by a set screw 17. Meanwhile, the other end 14" of thelink shaft 14 is rotatably passed through a bushing 19 secured to theside face of the grinding wheel guard 5 as shown in FIG. 3. The threadedend portions 14a of the link shaft 14 projects into the grinding wheelguard 5. A lever 21 is fixed with 'nuts 20, 20 to the threaded endportions 14a and a large diameter grinding wheel rejecting pin 22 isfixed on the lever 21 by means of the threaded portion 22a and a nut 23,as shown in FIG. 3. At the pulley side end 14' of the link shaft 14, arotatable arm 24 acting as a leaf spring is fixed to the rotatable boss16. On one end of the rotatable arm 24 a safety arm 26 is rotatablymounted by means of a support pin 27. A high-speed pulley rejecting pin25 which extends into a recess in the pulley 4 or 33 is secured to thesafety ann 26, as shown in FIG. 3. Approximately midway on thesafety arm26 a guide slot 260 is formed for slidably receiving a guide pin 28. Theguide pin 28 is fastened on the grinding wheel head 1 through a support29, as shown in FIG. 3.

Turning of the link shaft 14 can be accomplished by an operating lever30. This motion is transmitted by the rotatable arm 24 via the supportpin 27 to the safety arm 26. When a knob such as 35 is used, theoperating lever 30 is made to fit into an engaging hole 31 or 32provided on the plate 13 and the safety arm 26 slides along the guideslot 26a. Thereby the high-speed pulley rejecting pin 25 provided at theend of the safety arm 26 occupies the position 25 or 25, as shown inFIG. 3. When the operating lever 30 fits into the engaging hole 31, thelarge-diameter grinding wheel rejecting pin 22 occupies the position 22,and when the lever 30 fits into the hole 32, the pin 22 occupies theposition 22', shown in FIGS. 1 and 3 Safety is attained with the presentarrangement in the following manner. During the grinding operation inthe state of FIG. 1, when the grinding wheel is reduced in diameter fromdiameter a to diameter b, a pulley exchange is required and theoperating lever 30 is turned to the position at which it fits into thehole 32 bored on the plate 13. The high-speed pulley rejecting pin 25shifts to the position where it does not obstruct the small-diameterhigh-speed pulley 33 (position 25' in H6. 3). On the other hand, thelarge diameter grinding wheel rejecting pin 22 as the result of the linkshaft 14 being turned stops at the position 22' in FIGS. 1 and 3 therebymatching the reduced diameter 1: requiring the pulley exchange. In thiscondition it is impossible to mount a large-diameter (diameter a)grinding wheel 3. In order to dismount the low-speed pulley, mount thehigh-speed one, and retighten the V-belts 34, the positions of the motor8 and the pulley 18 mounted on its shaft relative to the grinding wheelspindle 2 may be adjusted by the hand wheel 12.

As the grinding wheel is further reduced in diameter from diameter b todiameter c, another pulley exchange is required before a newlarge-diameter wheel replaces the worn out wheel. The large-diametergrinding wheel rejecting pin 22 at the position 22' impedes the mountingof large-diameter (diameter a) grinding wheel 3. The pin 22 must bemoved to the position 22 in FIG. 1. For this purpose, the operatinglever is turned to the position where it fits into the hole 31 bored onthe plate 13. However, the high-speed pulley rejecting pin 25 of thesafety arm 26 is restricted to the position 25' in FIG. 3 by the insidesurface 33' of the small-diameter high-speed pulley 33 and therebyprevents the turning of the link shaft 14. In other words, the mountingof a large-diameter (diameter a) grinding wheel 3 is only possible afterthe small-diameter highspeed pulley 33, is replaced by thelarge-diameter low-speed pulley 4, thereby permitting the high-speedpulley rejecting pin 25 to be displaced up to the inside surface 4 ofthe lowspeed pulley 4. This permits the large-diameter grinding wheelrejecting pin 22 to move from 22' to 22.

According to the present invention, the hazard in a grinding operationis easily eliminated by a safety device simple in construction and easyto operate. When the small-diameter highspeed pulley 33 is on, thehigh-speed pulley rejecting pin 25 is obstructed by the high-speedpulley 33. Accordingly, the mountingof a large-diameter grinding wheelhaving a diameter a is impossible because of the positions of thesafet'yann 26 and the large-diameter grinding wheel-rejecting pin 22.Therefore, the low-speed pulley 4 must be mounted before a largediameter(diameter a) grinding wheel 3 can be mounted. Thus, circumferentialoverspeeding of a large-diameter (diameter a) grinding wheel 3 caused byoperation with a high-speed pulley 33 is absolutely impossible.Meanwhile, it is possible to secure an adequate circumferential speed ofa reduced-diameter grinding wheel, if the pulley is changed to ahigh-speed pulley 33. However, it is impossible to mount a high-speedpulley 33 for a large-diameter wheel whereby dangerous overspeeding isprevented.

What is claimed is:

1. An apparatus for preventing circumferential overspeeding of agrinding wheel through exchange of small and largediameter grindingwheel spindle pulleys in a grinding machine wherein the rotary speed ofthe grinding wheel spindle is variable by pulley exchange comprising agrinding wheel head with the grinding wheel spindle rotatably mountedthereto and a motor connected to drive the grinding wheel spindle,operating means supported by a mounting plate'secured to the pulley sideend face of the grinding wheel head, a large-diameter grinding wheelrejecting pin fixed to the operating means and constructed and arrangedrelative to the grinding wheel spindle to obstruct the space tobeoccupied by a large-diameter v v grinding wheel on the spindle andthereb prevent the mounting of a large-diameter grinding wheel w en thesmall-diameter high-speed pulley is on the grinding wheel spindle, and ahigh-speed pulley rejecting pin fixed to the operating means andmechanically interlocked with the large-diameter grinding wheelrejecting pin constructed and arranged relative to the grinding wheelspindle to obstruct the space to be occupied by a high-speed pulley onthe spindle when the large-diameter grinding wheel is on the spindlethereby preventing the mounting of the high-speed pulley.

2. An apparatus as in claim 1 wherein the operating means is constructedand arranged to move the interlocked largediameter grinding wheelrejecting pin and high-speed pulley rejecting pin in the same direction,and the mounting plate is provided with holes for fixing the operatingmeans in positions for fitting the high-speed pulley and the low-speedpulley.

3. An apparatus as in claim 2 wherein the operating means includes arotatable link shaft parallel to the grinding wheel spindle about midwaybetween the grinding wheel spindle and the motor with the small-diameterhigh-speed pulley rejecting pin at the pulley side end of the link shaftand the large-diameter grinding wheel rejecting pin at the other end ofthe shaft.

4. An apparatus as in claim 3 wherein the operating means furtherincludes an operating lever secured to the link shaft and arranged to befixed to said holes, and a safety arm, one end of the safety arm isconnected to the operating lever and the other end thereof has thehigh-speed pulley rejecting pin.

1. An apparatus for preventing circumferential overspeeding of agrinding wheel through exchange of small and large-diameter grindingwheel spindle pulleys in a grinding machine wherein the rotary speed ofthe grinding wheel spindle is variable by pulley exchange comprising agrinding wheel head with the grinding wheel spindle rotatably mountedthereto and a motor connected to drive the grinding wheel spindle,operating means supported by a mounting plate secured to the pulley sideend face of the grinding wheel head, a large-diameter grinding wheelrejecting pin fixed to the operating means and constructed and arrangedrelative to the grinding wheel spindle to obstruct the space to beoccupied by a large-diameter grinding wheel on the spindle and therebyprevent the mounting of a large-diameter grinding wheel when thesmall-diameter high-speed pulley is on the grinding wheel spindle, and ahigh-speed pulley rejecting pin fixed to the operating means andmechanically interlocked with the largediameter grinding wheel rejectingpin constructed and arranged relative to the grinding wheel spindle toobstruct the space to be occupied by a high-speed pulley on the spindlewhen the largediameter grinding wheel is on the spindle therebypreventing the mounting of the high-speed pulley.
 2. An apparatus as inclaim 1 wherein the operating means is constructed and arranged to movethe interlocked large-diameter grinding wheel rejecting pin andhigh-speed pulley rejecting pin in the same direction, and the mountingplate is provided with holes for fixing the operating means in positionsfor fitting the high-speed pulley and the low-speed pulley.
 3. Anapparatus as in claim 2 wherein the operating means includes a rotatablelink shaft parallel to the grinding wheel spindle about midway betweenthe grinding wheel spindle and the motor with the small-diameterhigh-speed pulley rejecting pin at the pulley side end of the link shaftand the large-diameter grinding wheel rejecting pin at the other end ofthe shaft.
 4. An apparatus as in claim 3 wherein the operating meansfurther includes an operating lever secured to the link shaft andarranged to be fixed to said holes, and a safety arm, one end of thesafety arm is connected to the operating lever and the other end thereofhas the high-speed pulley rejecting pin.